A specially commissioned sculpture was unveiled and flowers laid in memory of the dead.

During the public service, which begins at a local school at 1430 BST, ten candles will be lit - seven for those who died and one each for the injured, the emergency services and the local community.

"This happened in the heart of the community in Potters Bar and a lot of people were involved and will remember that fateful afternoon very clearly," a spokesman for the Diocese of St Albans told BBC News Online.

'Terribly hurtful'

The first anniversary has led to renewed calls for more to be done to establish the cause of the tragedy.

The call for a public inquiry is backed by Louise Christian, the solicitor representing some of the families and survivors.

Author Nina Bawden, 77, who was severely injured and lost her husband Austen Kark, said it was "terribly hurtful" that nobody had been held to account.